The calcium sulfate statolith-synthesizing system of Aurelia will be used as a model system for the study of calcification mechanisms in biological systems. Using radioautographic techniques and EM-radioautographic methods, the uptake of labeled calcium, phosphate, sulphate, and proline will be observed and traced throughout the statolith-synthesizing cells. Efforts to find sites of concentration of these substances in these cells will be made, and, if possible, correlated with sites of "nucleation" prior to statolith formation. Uptake of calcium and phosphate will be compared in normal and sulfate-deficient organisms to determine whether sulfate concentration in rhopalia of these organisms influences the uptake and/or concentration of other ions. The role of protein synthesis in early statolith differentiation will be determined and the possible role of alkaline phosphatase and pyrophosphates in statolith synthesis will be investigated.